Abstract
While there has been remarkable progress in understanding the biology of HIV-1 and its recognition by the human immune system, we have not yet developed an efficacious HIV-1 vaccine. Vaccine challenges include the genetic diversity and mutability of HIV-1 which create a plethora of constantly changing antigens, the structural features of the viral envelope glycoprotein that disguise conserved receptor-binding sites from the immune system, and the presence of carbohydrate moieties that shield potential epitopes from antibodies. Despite these challenges, there has been significant scientific progress in recent years. In 2009, a large-scale clinical trial known as RV144 demonstrated that a HIV-1 vaccine could modestly reduce the incidence of HIV-1 infection. Further, the identification of broadly neutralizing monoclonal antibodies (such as VRC01, a human monoclonal antibody capable of neutralizing over 90% of natural HIV-1 isolates, as well as PG and PGT antibodies that recognize conserved glycopeptide epitopes) has revealed new opportunities for vaccine design. Our ability to understand HIV-1 structure and antibody epitopes at the atomic level, the rapid advance of computational and bioinformatics approaches to immunogen design, and our newly acquired knowledge that it is possible for a vaccine to reduce the risk of HIV-1 infection, have all opened up new and promising pathways towards the development of an urgently needed effective HIV-1 vaccine. This article summarizes challenges to the development of an HIV-1 vaccine, lessons learned from scientific investigation and completed vaccine trials, and promising developments in HIV-1 vaccine design.